Bone cancer and multiple myeloma affects over 600,000 people every year in the United States and causes progressive bone destruction that results in pain, fractures, and the inability to walk. The hypothesis of the proposal is that thermal ablation with high intensity interstitial ultrasound (HIIU) is efficacious in management of metastatic bone cancer. We propose to develop a mechanism to perform minimally invasive conformal bone ablation under combined computer tomography (CT) and CT fluoroscopy (CTF) guidance. We will prove that this method provides a consistent, reliable, and safe treatment option in a simple and cost-efficient manner. We propose classic medical technology development accomplished in two steps: first the development of appropriate core technology, and then the evaluation of that in a Phase-1 clinical trial. The deliverables of the program will be (1) an advanced prototype of an integrated medical device that is ready for regulatory approval and subsequent commercial introduction, (2) clinical methodology for the use of this device to treat metastatic spine cancer. In particular, we will apply acoustic ablative needles to be inserted percutaneously into the bone near the target. Phase-1 research will establish the feasibility of safe and accurate percutaneous HIIU needle placement and ablation under real-time quantitative CT/CTF guidance. Specific aims are as follows: Aim-1: Image Guidance: Develop methodology, hardware, and software components for sterotactic image guidance of the ablator device and intra-operative optimization of the ablation. Aim-2: HIIU Applicator: Package an acoustic ablator catheter in a needle for percutaneous introduction to bony tissues, compliant to the guidance method developed in Aim-1. Aim-3: Animal Studies: Perform feasibility studies in ex-vivo and in-vivo animal models with the system developed in Aims 1 and 2.